Network Engineer Interview - Questions & Answers


Question: Tell us something about Cisco PPDIOO Life-cycle approach?
ANS: PPDIOO stands for Prepare, Plan, Design, Implement, Operate, and Optimize. The PPDIOO life-cycle approach is somewhat similar to the IT Information Library (ITIL) framework in that both provide a network service’s life-cycle framework to help ensure that when the project is implemented the entire company will have everything it needs to operate and maintain the new network. The Cisco PPDIOO model encompasses all steps, from network vision to optimization. Figure 1-1 below is an illustration of the different phases of the PPDIOO life-cycle approach.
 





Question: What are typical virus sources and how do you prevent virus attacks?
ANS: Source of Computer virus:

        Downloadable Programs, Cracked Software, Email Attachments, Internet and Booting from CD

Preventing Virus attack: Install quality antivirus, Install real-time anti-spyware protection,                Keep anti-malware applications current, Perform daily scans, Disable auto run, Disable image previews in Outlook, Don't click on email links or attachments, Surf smart, Use a hardware-based firewall and Deploy DNS protection


Question. What are some of the things you need to take into consideration when planning an upgrade from one network operating system to another?
ANS. This is the mother of all planning activities because it will affect so many resources. The key here is testing and backups and that’s what the interviewer wants to hear. Other considerations include:

·         Network documentation

·         Ensuring that your hardware meets the minimum hardware requirements for the new operating system

·         Creating a test network for testing the compatibility of applications, hardware, and drivers with the new operating system

·         Gathering all updated drivers and patches/service packs required for upgrade compatibility

·         Identifying workflow issues before converting

·         Separating workstation conversions from server conversions

·         Ensuring you have backups of data and the servers so that you can revert back
Network addressing scheme


Q. How would you ensure that your servers are secure?
ANS. Security always begins at the physical level—it makes little difference that you’ve provided all the security the operating system and software can provide if someone can walk away with the box or the portable hard drive. The next step is to ensure you have the latest service packs for the operating system and applications running on the server.



Question. A user contacts you and reports that their Windows 2000 workstation is having trouble connecting to the Web. You run the ipconfig command on the computer and you find that the computer is not referencing the correct primary DNS server. What must you do to remedy this?
ANS. Using this question, the interviewer can assess your routing troubleshooting skills, an essential part of network administration. In this case, you would want to check the primary DNS setting in the IP configuration of the computer. If ipconfig shows a setting for the default DNS server other than what you want, this means the computer’s IP configuration is incorrect. Therefore, the Windows 2000 client computer needs to be reconfigured.




Question. What is Service Level Agreement?
ANS: A service level agreement (SLA) is a contract between a service provider (either internal or external) and the end user that defines the level of service expected from the service provider. SLAs are output-based in that their purpose is specifically to define what the customer will receive.



Question. Which three commands can be used to check LAN connectivity problems on a router?
ANS:  
1.    show interfaces
2.    show ip route
3.    ping



Qustion What is SMTP & SNM?
ANS: SMTP: SMTP stands for Simple Mail Transfer Protocol. It deals with the methods, to send and receive email from one client to another over the internet. It has a wide breadth that covers the mail servers and the applications that are used to send/receive emails. When you compose a mail and send it, the SMTP client communicates with the mail server and verifies the information about the email and the destination. Then the SMTP server sends your mail to the destination, and their SMTP client handles the receiving process in the same manner.

SNMP: SNMP stands for Simple Network Management Protocol. As the name suggests, it manages various devices attached to a TCP / IP network. There are three tiers in this protocol. The SNMP Manager, SNMP Agent and the Managed Device. SNMP Manager is essentially a controller while SNMP Agent acts as an interface between the devices and the network. The Managed Device is the device that is controlled by the above two.

SNMP and SMTP are two standards that work together in harmony to achieve two different tasks. They work in such a way that one can control SMTP servers and MTAs through SNMP Managers. Further, SNMP Managers are capable of sending alerts through SMTP mail servers.


Question. How does Frame Relay Work?
ANS: Frame relay is a packet-switching telecommunication service designed for cost-efficient data transmission for intermittent traffic between local area networks (LANs) and between endpoints in wide area networks (WANs).


Question. What is ATM technology?

ANS: ATM is a connection-oriented, unreliable (does not acknowledge the receipt of cells sent), virtual circuit packet switching technology. The cost of maintaining separate, specialized networks for computer, voice, and video is high. To reduce networking costs, ATM enables integration of all of these services on a single network and the combination of existing networks into a single infrastructure. In particular, Windows operating systems provide rich connectivity using Asynchronous Transfer Mode (ATM) while maintaining support for legacy systems.



Question. How does the DSL work?

ANS: When you connect to the Internet, you might connect through a regular modem, through a local-area network connection in your office, through a cable modem or through a digital subscriber line (DSL) connection. DSL is a very high-speed connection that uses the same wires as a regular telephone line.


Question. Do you know about MPLS?

ANS: (MPLS is that it’s a technique, not a service) - Multiprotocol Label Switching (MPLS) is a type of data-carrying technique for high-performance telecommunications networks that directs data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in a routing table. MPLS operates at a layer that is generally considered to lie between traditional definitions of OSI Layer 2 (data link layer) and Layer 3 (network layer), and thus is often referred to as a layer 2.5 protocol.


Question. How does MPLS work?

ANS: In MPLS, packets are directed through the network based on an assigned label. The label is associated with a predetermined path through the network, which allows a higher level of control than in packet-switched networks. MPLS routing allow differing Qos characteristics and priorities to be assigned to particular data flows, and operators can predetermine fallback paths in the event that traffic must be rerouted.


Question. What is VRF?

ANS: Virtual routing and forwarding (VRF) is a technology included in IP (Internet Protocol) network routers that allows multiple instances of a routing table to exist in a router and work simultaneously. This increases functionality by allowing network paths to be segmented without using multiple devices. Because traffic is automatically segregated, VRF also increases network security and can eliminate the need for encryption and authentication. Internet service providers (ISPs) often take advantage of VRF to create separate virtual private networks (VPNs) for customers; thus the technology is also referred to as VPN routing and forwarding.



Question. What is MPLS VPN?

ANS: Multiprotocol Label Switching (MPLS) is a standards-based technology used to speed up the delivery of network packets over multiple protocols – such as the Internet Protocol (IP), Asynchronous Transport Mode (ATM) and frame relay network protocols.

A virtual private network (VPN) uses shared public telecom infrastructure, such as the Internet, to provide secure access to remote offices and users in a cheaper way than an owned or leased line. VPNs are secure because they use tunneling protocols and procedures such as Layer Two Tunneling Protocol (L2TP)


Question. What is difference between Route Distinguisher and Route Target.

ANS: The Route-Distinguisher (RD) & Route-Target (RT) are two different concepts that are both used in an MPLS VPN. The RD is used to keep all prefixes in the BGP table unique, and the RT is used to transfer routes between VRF’s/VPNS.


Question. What is VPLS

ANS: Virtual Private LAN Service (VPLS) is a way to provide Ethernet-based multipoint to multipoint communication over IP or MPLS networks. It allows geographically dispersed sites to share an Ethernet broadcast domain by connecting sites through pseudo-wires. The term 'sites' includes multiplicities of both servers and clients. The technologies that can be used as pseudo-wire can be Ethernet over MPLS, L2TPv3 or even GRE. There are two IETF standards track RFCs (RFC 4761 and RFC 4762) describing VPLS establishment.
 
June 03, 2016